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