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)(11,21)(12,25)(13,17)(14,19)(15,31)(16,20)(18,29)(22,38)(23,33)(24,34)(26,32)(27,40)(28,37)(30,36)(35,39) involution — undirected(9,11,16,23)(10,17,20,34)(12,26,29,30)(13,15,24,14)(18,35,25,38)(19,33,31,21)(22,28,39,27)(32,40,36,37)(2,5)(6,8)(9,12,14,27,16,29,15,28)(10,18,19,37,20,25,31,40)(11,22,24,26,23,39,13,30)(17,32,21,35,34,36,33,38)(9,13,14,11,16,24,15,23)(10,17,19,21,20,34,31,33)(12,26,27,39,29,30,28,22)(18,36,37,38,25,32,40,35)(1,3,4,7)(2,6,5,8)(9,14,16,15)(10,19,20,31)(11,13,23,24)(12,27,29,28)(17,33,34,21)(18,37,25,40)(22,30,39,26)(32,38,36,35)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.