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