One vertex per element, one color per generator, with an edge from x to x·s.
(1,2)(3,8)(4,6)(5,7)(9,10)(11,20)(12,24)(13,18)(14,17)(15,22)(16,27)(19,28)(21,38)(23,33)(25,37)(26,36)(29,32)(30,35)(31,40)(34,39) involution — undirected(1,3,5,4)(2,6,7,8)(9,11,13,22)(10,15,18,20)(12,25,26,40)(14,29,28,23)(16,34,35,38)(17,33,19,32)(21,30,39,27)(24,31,36,37)(9,12,13,26)(10,16,18,35)(11,21,22,39)(14,30,28,27)(15,31,20,37)(17,24,19,36)(23,40,29,25)(32,34,33,38)(1,4,5,3)(2,6,7,8)(10,17)(14,28)(15,32)(16,24)(18,19)(20,33)(23,29)(25,40)(27,30)(31,34)(35,36)(37,38)(2,7)(6,8)(10,18)(12,26)(15,20)(17,19)(21,39)(25,40)(27,30)(32,33) involution — undirectedA 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.