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