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