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