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