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