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