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)(12,15)(13,18)(14,16)(19,24)(20,22)(21,23)(25,26)(27,37)(28,33)(29,34)(30,35)(31,36)(32,38)(39,40)(1,2)(3,6)(4,7)(5,8)(9,11,14,12)(10,15,16,17)(13,19,21,20)(18,22,23,24)(25,27)(26,32)(28,39)(29,35)(30,40)(31,38)(33,34)(36,37)(10,16)(15,17)(18,23)(22,24)(27,38)(29,39)(32,37)(34,40) involution — undirected(1,3,5,4)(2,6,8,7)(9,10)(11,15)(12,17)(13,18)(14,16)(19,22)(20,24)(21,23)(25,28,31,35)(26,33,36,30)(27,39,38,29)(32,34,37,40)(9,12,14,11)(10,17,16,15)(13,20,21,19)(18,24,23,22)(25,29,31,39)(26,34,36,40)(27,35,38,28)(30,32,33,37)(1,4,5,3)(2,7,8,6)(9,13,14,21)(10,18,16,23)(11,19,12,20)(15,22,17,24)(25,30,31,33)(26,35,36,28)(27,34,38,40)(29,32,39,37)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.