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