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