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