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