One vertex per element, one color per generator, with an edge from x to x·s.
(1,2,5,8)(3,6,4,7)(9,10)(11,17)(12,19)(13,15)(14,16)(18,21)(20,23)(22,24)(25,26,31,35)(27,36,39,32)(28,33,40,29)(30,34,38,37)(1,2)(3,6)(4,7)(5,8)(9,11)(10,12)(13,18)(14,19)(15,20)(16,17)(21,24)(22,23)(25,27)(26,32)(28,34)(29,38)(30,33)(31,39)(35,36)(37,40) involution — undirected(9,10,14,16)(11,17,19,12)(13,15,22,24)(18,21,23,20)(25,28)(26,33)(27,37)(29,35)(30,36)(31,40)(32,38)(34,39)(1,3,5,4)(2,6,8,7)(9,10)(11,12)(13,15)(14,16)(17,19)(18,20)(21,23)(22,24)(25,29,31,33)(26,28,35,40)(27,38,39,30)(32,34,36,37)(1,4,5,3)(2,7,8,6)(9,12)(10,11)(13,21)(14,17)(15,23)(16,19)(18,24)(20,22)(25,28)(26,33)(27,34)(29,35)(30,32)(31,40)(36,38)(37,39)(9,13,14,22)(10,15,16,24)(11,18,19,23)(12,20,17,21)(25,30,31,38)(26,34,35,37)(27,33,39,29)(28,36,40,32)A Cayley diagram is a choice, not a fact about the group. Another drawing of this group — in a book, or on a different generating set — may look nothing like this one.