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