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