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