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